Pneumatic tire

Abstract

A pneumatic tire includes a tread portion having a first tread edge, and a first buttress portion extending inwardly in a tire radial direction from the first tread edge. The first buttress portion is provided with a plurality of protectors protruding outwardly in a tire axial direction. Each of the plurality of protectors includes a top surface facing outwardly in the tire axial direction, and a side surface extending inwardly in the tire axial direction from an edge of the top surface. The side surface includes an outward-facing portion facing outwardly in the tire radial direction, an inward-facing portion facing inwardly in the tire radial direction, and a circumferential portion facing in a tire circumferential direction. The outward-facing portion, the inward-facing portion and the circumferential portion have different angles with respect to respective normal lines of the top surface from each other.

The invention claimed is: 
     
       1. A pneumatic tire comprising:
 a tread portion having a first tread edge, and 
 a first buttress portion extending inwardly in a tire radial direction from the first tread edge, wherein 
 the first buttress portion is provided with a plurality of protectors protruding outwardly in a tire axial direction, 
 each of the plurality of protectors comprises a top surface facing outwardly in the tire axial direction, and a side surface extending inwardly in the tire axial direction from an edge of the top surface, 
 the side surface comprises an outward-facing portion facing outwardly in the tire radial direction, an inward-facing portion facing inwardly in the tire radial direction, and a circumferential portion facing in a tire circumferential direction, 
 the outward-facing portion, the inward-facing portion and the circumferential portion have different angles with respect to respective normal lines of the top surface from each other, 
 the plurality of protectors comprises at least one first protector having an L-shape protruding towards a first side in the tire circumferential direction and a second protector being spaced from and adjacent to the at least one first protector on a second side in the tire circumferential direction to form a groove extending in the tire radial direction between the at least one first protector and the second protector, 
 the groove is provided with a localized tie-bar connecting the at least one first protector and the second protector with a protruding height smaller than those of the at least one first protector and the second protector, 
 the at least one first protector includes a single outward-facing portion, and two inward-facing portions, 
 the two inward-facing portions include a first inward-facing portion that is inclined outwardly in the tire radial direction toward the first side in the tire circumferential direction and a second inward-facing portion inclined inwardly in the tire radial direction toward the first side in the tire circumferential direction, 
 the second protector has an inverted L-shape protruding towards the second side in the tire circumferential direction, 
 the tie-bar has a circumferentially extending radially outermost edge being inclined outwardly in the tire radial direction toward the first side in the tire circumferential direction, 
 the outermost edge is located inwardly in the tire radial direction with respect to a radially outermost end of the outward-facing portion of the at least one first protector, 
 each of the plurality of protectors comprises an outer portion and an inner portion located inwardly in the tire radial direction of the outer portion, and 
 a maximum length in the tire circumferential direction of the outer portion is smaller than a maximum length in the tire circumferential direction of the inner portion. 
 
     
     
       2. A pneumatic tire comprising:
 a tread portion having a first tread edge, and 
 a first buttress portion extending inwardly in a tire radial direction from the first tread edge, wherein 
 the first buttress portion is provided with a plurality of protectors protruding outwardly in a tire axial direction, 
 each of the plurality of protectors comprises a top surface facing outwardly in the tire axial direction, and a side surface extending inwardly in the tire axial direction from an edge of the top surface, 
 the side surface comprises an inward-facing portion facing inwardly in the tire radial direction, and a circumferential portion facing in a tire circumferential direction, 
 the inward-facing portion and the circumferential portion have different angles with respect to respective normal lines of the top surface from each other, 
 the plurality of protectors comprises at least one first protector having an L-shape protruding towards a first side in the tire circumferential direction and a second protector being spaced from and adjacent to the at least one first protector on a second side in the tire circumferential direction to form a groove extending in the tire radial direction between the at least one first protector and the second protector, 
 the groove is provided with a localized tie-bar connecting the at least one first protector and the second protector with a protruding height smaller than those of the at least one first protector and the second protector, 
 the at least one first protector includes a single outward-facing portion, and two inward-facing portions, 
 the two inward-facing portions include a first inward-facing portion that is inclined outwardly in the tire radial direction toward the first side in the tire circumferential direction and a second inward-facing portion inclined inwardly in the tire radial direction toward the first side in the tire circumferential direction, 
 the second protector has an inverted L-shape protruding towards the second side in the tire circumferential direction, 
 the tie-bar has a circumferentially extending radially outermost edge being inclined outwardly in the tire radial direction toward the first side in the tire circumferential direction, 
 the outermost edge is located inwardly in the tire radial direction with respect to a radially outermost end of the outward-facing portion of the at least one first protector, 
 each of the plurality of protectors comprises an outer portion and an inner portion located inwardly in the tire radial direction of the outer portion, and 
 a maximum length in the tire circumferential direction of the outer portion is smaller than a maximum length in the tire circumferential direction of the inner portion. 
 
     
     
       3. The pneumatic tire according to  claim 1 , wherein an angle θi of the first and second inward-facing portions with respect to the normal line is smaller than an angle θc of the circumferential portion with respect to the normal line. 
     
     
       4. The pneumatic tire according to  claim 3 , wherein a difference (θc−θi) between the angle θc of the circumferential portion with respect to the normal line and the angle θi of the first and second inward-facing portions with respect to the normal line is in a range from 10 to 25 degrees. 
     
     
       5. The pneumatic tire according to  claim 1 , wherein
 an angle θi of the first and second inward-facing portions with respect to the normal line is equal to or less than 35 degrees, and 
 an angle θc of the circumferential portion with respect to the normal line is in a range from 5 to 45 degrees. 
 
     
     
       6. The pneumatic tire according to  claim 1 , wherein an angle θc of the circumferential portion with respect to the normal line is smaller than an angle θo of the outward-facing portion with respect to the normal line. 
     
     
       7. The pneumatic tire according to  claim 6 , wherein a difference (θo−θc) between the angle θo of the outward-facing portion with respect to the normal line and the angle θc of the circumferential portion with respect to the normal line is in a range from 10 to 25 degrees. 
     
     
       8. The pneumatic tire according to  claim 6 , wherein the angle θo of the outward-facing portion with respect to the normal line is in a range from 15 to 60 degrees. 
     
     
       9. The pneumatic tire according to  claim 1 , wherein the top surface is provided with a border portion extending along the edge of the top surface. 
     
     
       10. The pneumatic tire according to  claim 9 , wherein the border portion extends along an edge part forming the inward-facing portion and an edge part forming the circumferential portion. 
     
     
       11. The pneumatic tire according to  claim 9 , wherein the border portion has a projecting body protruding outwardly in the tire axial direction. 
     
     
       12. The pneumatic tire according to  claim 11 , wherein the projecting body, in a cross-sectional view thereof, consists of a semi arc-shaped surface having a radius of curvature of from 0.2 to 2 mm. 
     
     
       13. The pneumatic tire according to  claim 1 , wherein
 the single outward-facing portion is inclined inwardly in the tire radial direction toward the tire circumferential direction, and 
 a portion between the single outward-facing portion and the first inward-facing portion of the at least one first protector tapers toward the tire circumferential direction. 
 
     
     
       14. The pneumatic tire according to  claim 1 , wherein a length of the second inward-facing portion is shorter than a length of the first inward-facing portion. 
     
     
       15. The pneumatic tire according to  claim 1 , wherein a length of the first inward-facing portion is longer than a length of the single outward-facing portion. 
     
     
       16. The pneumatic tire according to  claim 1 , wherein the tie-bar has a circumferentially extending radially innermost edge being inclined outwardly in the tire radial direction toward the first side in the tire circumferential direction. 
     
     
       17. The pneumatic tire according to  claim 2 , wherein the tie-bar has a circumferentially extending radially innermost edge being inclined outwardly in the tire radial direction toward the first side in the tire circumferential direction. 
     
     
       18. The pneumatic tire according to  claim 1 , wherein
 the groove is provided with only a single localized tie-bar connecting the at least one first protector and the second protector with a protruding height smaller than those of the at least one first protector and the second protector, 
 the second protector includes a circumferential portion adjacent to the at least one first protector in the tire circumferential direction, 
 the circumferential portion adjacent to the at least one first protector in the tire circumferential direction extends radially inwardly from a radially outermost end of the second protector along the tire radial direction in a straight manner over an entire length thereof and 
 one end in the tire circumferential direction of the tie-bar is connected to the circumferential portion adjacent to the at least one first protector in the tire circumferential direction. 
 
     
     
       19. A pneumatic tire comprising:
 a tread portion having a first tread edge, and 
 a first buttress portion extending inwardly in a tire radial direction from the first tread edge, wherein 
 the first buttress portion is provided with a plurality of protectors protruding outwardly in a tire axial direction, 
 each of the plurality of protectors comprises a top surface facing outwardly in the tire axial direction, and a side surface extending inwardly in the tire axial direction from an edge of the top surface, 
 the side surface comprises an inward-facing portion facing inwardly in the tire radial direction, and a circumferential portion facing in a tire circumferential direction, 
 the inward-facing portion and the circumferential portion have different angles with respect to respective normal lines of the top surface from each other, 
 the plurality of protectors comprises at least one first protector having an L-shape protruding towards a first side in the tire circumferential direction and a second protector being spaced from and adjacent to the at least one first protector on a second side in the tire circumferential direction to form a groove extending in the tire radial direction between the at least one first protector and the second protector, 
 the groove is provided with only a single localized tie-bar connecting the at least one first protector and the second protector with a protruding height smaller than those of the at least one first protector and the second protector, 
 the at least one first protector includes a single outward-facing portion, and two inward-facing portions, 
 the two inward-facing portions include a first inward-facing portion that is inclined outwardly in the tire radial direction toward the first side in the tire circumferential direction and a second inward-facing portion inclined inwardly in the tire radial direction toward the first side in the tire circumferential direction, 
 the second protector has an inverted L-shape protruding towards the second side in the tire circumferential direction, 
 the second protector includes a circumferential portion adjacent to the at least one first protector in the tire circumferential direction, 
 the tie-bar has a circumferentially extending radially outermost edge being inclined outwardly in the tire radial direction toward the first side in the tire circumferential direction, 
 the outermost edge is located inwardly in the tire radial direction with respect to a radially outermost end of the outward-facing portion of the at least one first protector, 
 the circumferential portion adjacent to the at least one first protector in the tire circumferential direction extends radially inwardly from a radially outermost end of the second protector along the tire radial direction in a straight manner over an entire length thereof, and 
 one end in the tire circumferential direction of the tie-bar is connected to the circumferential portion adjacent to the at least one first protector in the tire circumferential direction.